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Mr. Maurice Benson March 12, 2009 Page 4 7. Appendix B, Section 5.0, Implications, Paragraph 2; The aquifer test results data provided in Table 3-3 do not support the statement "...that most dieldrin in the NWC plume is comprised entirely of dieldrin sorbed to particles greater than 0.45 pm in size and, therefore, less susceptible to removal by pumping. Filtered groundwater samples (<0.45 Nm) from EW056A, LM190A, LM191A, and LM141AU all showed steady with increasing trends towards the end of the tests, further demonstrating the NWC dieldrin's ease of mobility, and sustainable extraction especially in areas where high dieldrin mass is still located. (See attached figures). 8. Appendix B, Section 5.0, Implications, Paragraph 3; The Section states that water levels observed during pumping never stabilized possibly due to dewatering effects from localized or regional pumping influences, yet there is no discussion of possible influences presented in this section, or the groundwater performance evaluation and hydraulic data report sections. The feasibility study should be amended to possibly identify these mentioned pumping influences to better understand the other mechanisms which may have influenced the mass removal testing results. 9. Section 8.0, Table 8-1, Screening of Groundwater Remediation Technologies and Process Options; The process options Groundwater Use Restrictions and Groundwater Monitoring under the General Response of Land Use Controls do not realistically account for the groundwater rights or access rights to the offsite property owned by the Alvarez family. Access and groundwater rights to the private land would be required as a component of the land use controls specifically allowing for sampling of compliance monitoring point(s) and ensuring that no wells are installed adjacent to the DDJC-Tracy northwestern property boundary to eliminate the potential mobility of dieldrin by localized pumping influences. The results from the mass removal test data coupled with the Theis Groundwater Analysis prepared by DTSC's Geologic Services Unit (GSU) Modeler indicates that.a border zone encompassing the existing dieldrin plume is needed toIensure that no pumping influences are installed or operated in relative proximity of the existing plume to eliminate the potentially mobility of the NWC dieldrin plume. The actual distances provided in the border zone should be determined based on fieldwork data, supported by modeling and monitoring results. 10. Section 8.0, Table 8-1, Screening of Groundwater Remediation Technologies and Process Options, In-situ Treatment; While literature primarily states that